ImageReadParam and
ImageWriteParam.
This class provides mechanisms to specify a source region and a destination region. When reading, the source is the stream and the in-memory image is the destination. When writing, these are reversed. In the case of writing, destination regions may be used only with a writer that supports pixel replacement.
Decimation subsampling may be specified for both readers and writers, using a movable subsampling grid.
Subsets of the source and destination bands may be selected.
IIOParamController for
this IIOParam object and returns the resulting
value. When this method returns true, all values
for this IIOParam object will be ready for the
next read or write operation. If false is
returned, no settings in this object will have been disturbed
(i.e., the user canceled the operation).
Ordinarily, the controller will be a GUI providing a user
interface for a subclass of IIOParam for a
particular plug-in. Controllers need not be GUIs, however.
The equals method implements an equivalence relation
on non-null object references:
x, x.equals(x) should return
true.
x and y, x.equals(y)
should return true if and only if
y.equals(x) returns true.
x, y, and z, if
x.equals(y) returns true and
y.equals(z) returns true, then
x.equals(z) should return true.
x and y, multiple invocations of
x.equals(y) consistently return true
or consistently return false, provided no
information used in equals comparisons on the
objects is modified.
x,
x.equals(null) should return false.
The equals method for class Object implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x and
y, this method returns true if and only
if x and y refer to the same object
(x == y has the value true).
Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.
IIOParamController is currently
installed. This could be the default if there is one,
null, or the argument of the most recent call
to setController.IIOParamController, if there
is one, regardless of the currently installed controller. If
there is no default controller, returns null. If setDestinationOffsets has not been called,
a Point with zero X and Y values is returned
(which is the correct value).
setDestination(ImageTypeSpecifier), as an
ImageTypeSpecifier. If none was set,
null is returned.setSourceBands, or null if there have
been no calls to setSourceBands.
Semantically, the array returned is a copy; changes to
array contents subsequent to this call have no effect on this
IIOParam.
setSourceRegion, and will be null if
there is no region set.If setSourceSubsampling has not been called, 1
is returned (which is the correct value).
If setSourceSubsampling has not been called, 1
is returned (which is the correct value).
If setSourceSubsampling has not been called, 0
is returned (which is the correct value).
If setSourceSubsampling has not been called, 0
is returned (which is the correct value).
true if there is a controller installed
for this IIOParam object. This will return
true if getController would not
return null.java.util.Hashtable.
The general contract of hashCode is:
hashCode method on each of
the two objects must produce the same integer result.
As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
wait methods.
The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
synchronized statement
that synchronizes on the object.
Class, by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
wait methods.
The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
IIOParamController to be used
to provide settings for this IIOParam
object when the activateController method
is called, overriding any default controller. If the
argument is null, no controller will be
used, including any default. To restore the default, use
setController(getDefaultController()). When reading, the region to be written within the
destination BufferedImage will start at this
offset and have a width and height determined by the source
region of interest, the subsampling parameters, and the
destination bounds.
Normal writes are not affected by this method, only writes
performed using ImageWriter.replacePixels. For
such writes, the offset specified is within the output stream
image whose pixels are being modified.
There is no unsetDestinationOffset method;
simply call setDestinationOffset(new Point(0, 0)) to
restore default values.
ImageTypeSpecifier.
When reading, if the layout of the destination has been set
using this method, each call to an ImageReader
read method will return a new
BufferedImage using the format specified by the
supplied type specifier. As a side effect, any destination
BufferedImage set by
ImageReadParam.setDestination(BufferedImage) will
no longer be set as the destination. In other words, this
method may be thought of as calling
setDestination((BufferedImage)null).
When writing, the destination type maybe used to determine
the color type of the image. The SampleModel
information will be ignored, and may be null. For
example, a 4-banded image could represent either CMYK or RGBA
data. If a destination type is set, its
ColorModel will override any
ColorModel on the image itself. This is crucial
when setSourceBands is used since the image's
ColorModel will refer to the entire image rather
than to the subset of bands being written.
A null value indicates that all source bands
will be used.
At the time of reading, an
IllegalArgumentException will be thrown by the
reader or writer if a value larger than the largest available
source band index has been specified or if the number of source
bands and destination bands to be used differ. The
ImageReader.checkReadParamBandSettings method may
be used to automate this test.
Semantically, a copy is made of the array; changes to the
array contents subsequent to this call have no effect on
this IIOParam.
setSourceSubsampling.
If subsampling has been set such that this number is zero,
an IllegalStateException will be thrown.
The source region of interest specified by this method will be clipped as needed to fit within the source bounds, as well as the destination offsets, width, and height at the time of actual I/O.
A value of null for sourceRegion
will remove any region specification, causing the entire image
to be used.
sourceXSubsampling and
sourceYSubsampling parameters specify the
subsampling period (i.e., the number of rows and columns
to advance after every source pixel). Specifically, a period of
1 will use every row or column; a period of 2 will use every
other row or column. The subsamplingXOffset and
subsamplingYOffset parameters specify an offset
from the region (or image) origin for the first subsampled pixel.
Adjusting the origin of the subsample grid is useful for avoiding
seams when subsampling a very large source image into destination
regions that will be assembled into a complete subsampled image.
Most users will want to simply leave these parameters at 0.
The number of pixels and scanlines to be used are calculated as follows.
The number of subsampled pixels in a scanline is given by
truncate[(width - subsamplingXOffset + sourceXSubsampling - 1)
/ sourceXSubsampling].
If the region is such that this width is zero, an
IllegalStateException is thrown.
The number of scanlines to be used can be computed similarly.
The ability to set the subsampling grid to start somewhere
other than the source region origin is useful if the
region is being used to create subsampled tiles of a large image,
where the tile width and height are not multiples of the
subsampling periods. If the subsampling grid does not remain
consistent from tile to tile, there will be artifacts at the tile
boundaries. By adjusting the subsampling grid offset for each
tile to compensate, these artifacts can be avoided. The tradeoff
is that in order to avoid these artifacts, the tiles are not all
the same size. The grid offset to use in this case is given by:
grid offset = [period - (region offset modulo period)] modulo period)
If either sourceXSubsampling or
sourceYSubsampling is 0 or negative, an
IllegalArgumentException will be thrown.
If either subsamplingXOffset or
subsamplingYOffset is negative or greater than or
equal to the corresponding period, an
IllegalArgumentException will be thrown.
There is no unsetSourceSubsampling method;
simply call setSourceSubsampling(1, 1, 0, 0) to
restore default values.
toString method returns a string that
"textually represents" this object. The result should
be a concise but informative representation that is easy for a
person to read.
It is recommended that all subclasses override this method.
The toString method for class Object
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `@', and
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify method or the
notifyAll method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait();
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.The current thread must own this object's monitor.
This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:
A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout);
... // Perform action appropriate to condition
}
(For more information on this topic, see Section 3.2.3 in Doug Lea's
"Concurrent Programming in Java (Second Edition)" (Addison-Wesley,
2000), or Item 50 in Joshua Bloch's "Effective Java Programming
Language Guide" (Addison-Wesley, 2001).
If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.
Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is similar to the wait method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:
notify method
or the notifyAll method.
timeout
milliseconds plus nanos nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout, nanos);
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.